25OHD2

25-hydroxyvitamin D2, also known as calcifediol or ergo-calcifediol, is a form of vitamin D produced in the body from ergocalciferol (vitamin D2). Vitamin D2 is primarily obtained from dietary sources, particularly fortified foods and some mushrooms. Upon ingestion or synthesis, vitamin D2 undergoes hydroxylation in the liver to become 25-hydroxyvitamin D2. This is the major circulating form of vitamin D in the blood and is used to assess vitamin D status. While 25-hydroxyvitamin D2 contributes to the body's overall vitamin D pool, 25-hydroxyvitamin D3 (produced from cholecalciferol, vitamin D3) is generally more abundant in most individuals. Both forms are then further metabolized in the kidneys to the active form, calcitriol. Measuring 25-hydroxyvitamin D levels, including both D2 and D3, is crucial for diagnosing and monitoring vitamin D deficiency or toxicity. High levels can indicate excessive supplementation, while low levels suggest inadequate intake or absorption.